Image forming apparatuses include fuser devices that fuse toner images to media such as paper sheets. Such a fuser device includes, for example, a heater that heats a sheet on which a toner image has been generated and a roller that applies pressure to the heated sheet. The fuser device heats and presses the medium to fix the toner image onto the medium. Heaters that can change a region to heat in accordance with the size of the medium are known.
However, such a heater may vary in temperature in a main scanning direction, for example.